Dynamics of influenza seasonality at sub-regional levels in India and implications for vaccination timing

Complete Genome Analysis of Influenza A(H1N1) Viruses Isolated in Kerala, India

Here, we report the complete sequence of four influenza A(H1N1) virus samples isolated from cases that occurred during the 2017 epidemic season in Kerala in South India. Sequence analysis showed mutations that differentiate this strain from the reference strain A/California/07/2009 virus.

Molecular characterization of Influenza A pandemic H1N1 viruses circulating in eastern India during 2017-19: Antigenic diversity in comparison to the vaccine strains

In the endemic settings of India, high CFR (3.6-7.02%) was observed in the consecutive 2009, 2015 and 2017 A/H1N1pdm09 outbreaks, though in eastern India CFR varied between 0 and 5.5% during same period. Recurrent outbreaks of pandemic Influenza A/H1N1pdm09, fragmented nationwide incidence data, lack of national policy for Influenza vaccination in India underscores the necessity for generating regional level data. Thus, during 2017-19, 4106 referred samples from patients hospitalized with severe acute respiratory illness (SARI) in eastern India were tested for A/H1N1pdm09 infection. Among which 16.5% (n = 677/4106) were found A/H1N1pdm09 positive. Individuals <20 years and middle-aged persons (40-60 years) were most susceptible to A/H1N1pdm09 infection. The vaccine strain (A/human/California/07/2009) which was globally used before 2017, clustered in a different lineage away from the representative eastern Indian strains in the phylogenetic dendrogram. The vaccine strain (A/human/Michigan/45/2015) used in India during the study period and the WHO recommended strain (A/human/Brisbane/02/2018) for 2019-20 flu season for the northern hemisphere, clustered with the circulating isolates in the same lineage-6b. Dissimilarities in the amino acids encompassing the antigenic epitopes were seen to be highest with the vaccine strain- A/human/California/07/2009. The significant amino acid variations in the circulating strains with the current WHO recommended vaccine strain, implies the exigency of continuous pandemic A/H1N1pdm09 surveillance studies in this epidemiological setting. The absence of any Oseltamivir resistant mutation (H275Y) in the neuraminidase gene of the current isolates suggests continuing use of Tamiflu® as an antiviral therapy in suspected subjects in this region.

Molecular characterization of influenza A(H1N1)pdm09 viruses circulating at various geographical locations in India, 2017

Background & objectives

Influenza virological surveillance is an essential tool for the early detection of novel genetic variants of epidemiologic and clinical significance. This study was aimed to genetically characterize A(H1N1)pdm09 virus circulating in 2017 and to compare it with the global data.

Methods

The regional/State Viral Research and Diagnostic Laboratories (VRDLs) provided influenza diagnosis for referred clinical samples and shared influenza A(H1N1)pdm09 positives with the Indian Council of Medical Research-National Institute of Virology (ICMR-NIV), Pune, India, for hemagglutinin (HA) gene phylogenetic analysis. Sites at Manipal, Jaipur and Dibrugarh performed the sequencing and shared the sequence data for analysis. The antiviral susceptibility of influenza viruses was assessed for known molecular marker H275Y at the ICMR-NIV, Pune.

Results

All the eight VRDLs had well-established influenza diagnostic facilities and showed increased activity of influenza A(H1N1)pdm09 during 2017. Phylogenetic analysis showed that the viruses from the different regions of the country were similar to A/Michigan/45/2015 strain which was the 2017-2018 recommended vaccine strain and were clustered with the globally circulating clade 6B.1 with signature mutations S84N, S162N and I216T. The clade 6B.1 showed further subgrouping with additional mutations S74R, S164T and I295V; however, there was no significant association between the presence of these mutations and severity of disease due to influenza. All the study viruses were sensitive to oseltamivir.

Interpretation & conclusions

During the study period, all the study sites reported globally circulating A/Michigan/45/2015 vaccine strain of influenza A(H1N1)pdm09 viruses and remained sensitive to oseltamivir. Further genetic and antigenic characterization of influenza viruses is recommended to address public health concerns.

Clinical practice guidelines 2019: Indian consensus-based recommendations on influenza vaccination in adults

Influenza, a common cause of acute respiratory infections, is an important health problem worldwide, including in India. Influenza is associated with several complications; people with comorbidities and the elderly are at a higher risk for such complications. Moreover, the influenza virus constantly changes genetically, thereby worsening therapeutic outcomes. Vaccination is an effective measure for the prevention of influenza. Despite the availability of global guidelines on influenza vaccination in adults, country-specific guidelines based on regional variation in disease burden are required for better disease management in India. With this aim, the Indian Chest Society and National College of Chest Physicians of India jointly conducted an expert meeting in January 2019. The discussion was aimed at delineating evidence-based recommendations on adult influenza vaccination in India. The present article discusses expert recommendations on clinical practice guidelines to be followed in India for adult influenza vaccination, for better management of the disease burden.

Hotspots of H1N1 influenza in India: analysis of reported cases and deaths (2010-2017)

Influenza A (H1N1) caused significant mortality and morbidity globally. We identified the hotspots for H1N1 influenza in India using cases and deaths reported in the Integrated Disease Surveillance Program between 2010 and 2017. A total of 114,667 cases and 8543 deaths were reported from across India, at an overall case fatality rate of 7.5%. While Maharashtra accounted for 21% of cases and 31% of deaths, Delhi and Gujarat were ranked the highest based on the population-adjusted ranks for morbidity and mortality, respectively. The current analysis identified states and union territories in western India (Delhi, Punjab, Rajasthan, Gujarat and Maharashtra) to be especially vulnerable.

Seasonal variation and etiologic inferences of childhood pneumonia and diarrhea mortality in India

Control of pneumonia and diarrhea mortality in India requires understanding of their etiologies. We combined time series analysis of seasonality, climate region, and clinical syndromes from 243,000 verbal autopsies in the nationally representative Million Death Study. Pneumonia mortality at 1 month-14 years was greatest in January (Rate ratio (RR) 1.66, 99% CI 1.51-1.82; versus the April minimum). Higher RRs at 1-11 months suggested respiratory syncytial virus (RSV) etiology. India's humid subtropical region experienced a unique summer pneumonia mortality. Diarrhea mortality peaked in July (RR 1.66, 1.48-1.85) and January (RR 1.37, 1.23-1.48), while deaths with fever and bloody diarrhea (indicating enteroinvasive bacterial etiology) showed little seasonality. Combining mortality at ages 1-59 months with prevalence surveys, we estimate 40,600 pneumonia deaths from Streptococcus pneumoniae, 20,700 from RSV, 12,600 from influenza, and 7200 from Haemophilus influenzae type b and 24,700 diarrheal deaths from rotavirus occurred in 2015. Careful mortality studies can elucidate etiologies and inform vaccine introduction.

Phylodynamics of Influenza A/H1N1pdm09 in India Reveals Circulation Patterns and Increased Selection for Clade 6b Residues and Other High Mortality Mutants

The clinical severity and observed case fatality ratio of influenza A/H1N1pdm09 in India, particularly in 2015 and 2017 far exceeds current global estimates. Reasons for these frequent and severe epidemic waves remain unclear. We used Bayesian phylodynamic methods to uncover possible genetic explanations for this, while also identifying the transmission dynamics of A/H1N1pdm09 between 2009 and 2017 to inform future public health interventions. We reveal a disproportionate selection at haemagglutinin residue positions associated with increased morbidity and mortality in India such as position 222 and clade 6B characteristic residues, relative to equivalent isolates circulating globally. We also identify for the first time, increased selection at position 186 as potentially explaining the severity of recent A/H1N1pdm09 epidemics in India. We reveal national routes of A/H1N1pdm09 transmission, identifying Maharashtra as the most important state for the spread throughout India, while quantifying climactic, ecological, and transport factors as drivers of within-country transmission. Together these results have important implications for future A/H1N1pdm09 surveillance and control within India, but also for epidemic and pandemic risk prediction around the world.

Dynamics of the occurrence of influenza in relation to seasonal variation in Chennai, Tamil Nadu: A 7 -year cumulative study

Background

Influenza viruses have emerged as virulent pathogens causing considerable burden across the world. A thorough understanding of the pattern in occurrence of influenza globally is the need of hour. The present study deals with analysis of the dynamics of Influenza virus, especially the influence of seasonal change on viral circulation and causation of epidemics/pandemics in the context of subtropical region.

Methods

During the 7 year (2009-2015) study, 36670 specimens were subjected to influenza analysis. Nasopharyngeal swabs collected from suspected patients from Chennai, Tamil Nadu, were tested and typed by real-time polymerase chain reaction assay.

Results

During 2009 pandemic, among influenza A positives 95.16% were Apdm09, indicating that there was a predominant circulation of Apdm09. During postpandemic period, there were waves in the occurrence of Apdm09 which indicates fall in immunity with buildup in the susceptible population.

Conclusion

In Chennai, Tamil Nadu, influenza positivity started with the onset of monsoon and peaks during the postmonsoon months throughout the study period. The assessment of meteorological factors compounding influenza activity can help in raising alerts to the public health officials of impending disaster which suggests that Influenza vaccination can be initiated before monsoon months in South India.

Randomized controlled trial of influenza vaccine in patients with heart failure to reduce adverse vascular events (IVVE): Rationale and design

BACKGROUND

Influenza is associated with an increase in the risk of cardiac and other vascular events. Observational data and small randomized trials suggest that influenza vaccination may reduce such adverse vascular events.

RESEARCH DESIGN AND METHODS

In a randomized controlled trial patients with heart failure are randomized to receive either inactivated influenza vaccine or placebo annually for 3 years. Patients aged ≥18 years with a clinical diagnosis of heart failure and NYHA functional class II, III and IV are eligible. Five thousand patients from 10 countries where influenza vaccination is not common (Asia, the Middle East, and Africa) have been enrolled. The primary outcome is a composite of the following: cardiovascular death, non-fatal myocardial infarction, non-fatal stroke and hospitalizations for heart failure using standardized criteria. Analyses will be based on comparing event rates between influenza vaccine and control groups and will include time to event, rate comparisons using Poisson methods, and logistic regression. The analysis will be conducted by intention to treat i.e. patients will be analyzed in the group in which they were assigned. Multivariable secondary analyses to assess whether variables such as age, sex, seasonality modify the benefits of vaccination are also planned for the primary outcome.

CONCLUSION

This is the largest randomized trial to test if influenza vaccine compared to control reduces adverse vascular events in high risk individuals.

TRIAL REGISTRATION NUMBER

Clinicaltrials.govNCT02762851.

Progress and Remaining Gaps in Estimating the Global Disease Burden of Influenza

Influenza has long been a global public health priority because of the threat of another global pandemic. Although data are available for the annual burden of seasonal influenza in many developed countries, fewer disease burden data are available for low-income and tropical countries. In recent years, however, the surveillance systems created as part of national pandemic preparedness efforts have produced substantial data on the epidemiology and impact of influenza in countries where data were sparse. These data are leading to greater interest in seasonal influenza, including implementation of vaccination programs. However, a lack of quality data on severe influenza, nonrespiratory outcomes, and high-risk groups, as well as a need for better mathematical models and economic evaluations, are some of the major gaps that remain. These gaps are the focus of multilateral research and surveillance efforts that will strengthen global efforts in influenza control in the future.

Immunogenicity and safety of an intramuscular split-virion quadrivalent inactivated influenza vaccine in individuals aged ≥ 6 months in India

A quadrivalent split-virion inactivated influenza vaccine (IIV4; Fluzone® Quadrivalent, Sanofi Pasteur) has been available in the US since 2013 for individuals aged ≥ 6 months. Here, we describe the results of an open-label, multicenter trial (WHO Universal Trial Number U1111-1143-8370) evaluating the immunogenicity and safety of IIV4 in Indian children aged 6-35 months and 3-8 years, adolescents aged 9-17 years, and adults aged ≥ 18 years (n = 100 per group). Post-vaccination hemagglutination inhibition titers for all strains in all age groups were ≥ 8 fold higher than at baseline (range, 8-51). At least 70% of participants in all age groups seroconverted or had a significant increase in titer for each strain. The most common solicited reactions were injection-site pain and tenderness, plus fever in participants 6-23 months and myalgia in older children and adolescents. All injection-site reactions and most systemic reactions were grade 1 or 2 and resolved within 3 days. Only three vaccine-related unsolicited adverse events were reported, all of which were grade 1 or 2 and transient. No immediate adverse events, adverse events leading to study discontinuation, adverse events of special interest, or serious adverse events were reported. This study showed that IIV4 was well tolerated and highly immunogenic in all age groups. This adds important data on the safety, tolerability, and immunogenicity of influenza vaccines in India.

Association between viral seasonality and meteorological factors

Numerous viruses can cause upper respiratory tract infections. They often precede serious lower respiratory tract infections. Each virus has a seasonal pattern, with peaks in activity in different seasons. We examined the effects of daily local meteorological data (temperature, relative humidity, “humidity-range” and dew point) from Edinburgh, Scotland on the seasonal variations in viral transmission. We identified the seasonality of rhinovirus, adenovirus, influenza A and B viruses, human parainfluenza viruses 1–3 (HPIV), respiratory syncytial virus (RSV) and human metapneumovirus (HMPV) from the 52060 respiratory samples tested between 2009 and 2015 and then confirmed the same by a generalised linear model. We also investigated the relationship between meteorological factors and viral seasonality. Non-enveloped viruses were present throughout the year. Following logistic regression adenovirus, influenza viruses A, B, RSV and HMPV preferred low temperatures; RSV and influenza A virus preferred a narrow “humidity-range” and HPIV type 3 preferred the season with lower humidity. A change (i.e. increase or decrease) in specific meteorological factors is associated with an increase in activity of specific viruses at certain times of the year.

Seasonal dynamics of influenza in Brazil: the latitude effect

BACKGROUND

Influenza is a global transmissible disease. Its dynamics is far better understood in temperate climates than in the tropics. We aim to close this knowledge gap between tropical and temperate regions by showing how the influenza seasonality evolves in Brazil, a tropical country that encompasses a wide range of latitudes and six climatic sub-types.

METHODS

We analyzed a state-level, weekly Syndrome of Acute Respiratory Disease (SARI) incidence data ranging from 2010 to 2016. We combined two techniques hierarchically: first the wavelet decomposition technique to detect annual periodicity and then circular statistics to describe seasonal measures of the periodic states.

RESULTS

We found significant annual periodicity in 44% of the states. For these, we calculated several seasonal measures such as the center of gravity or mean timing of activity. The relationship between the seasonal signatures and latitude was clear and statistically significant. States with seasonal signature are clustered along the coast. Most Amazonian and Central West states exhibit no seasonal behavior. Among the seasonal states, influenza starts in Northeast region, spreading southbound.

CONCLUSIONS

Our study advances the comprehension of influenza seasonality in tropical areas and could be used to design more effective prevention and control strategies.

Influenza B in a temperate region of northern India 2010-2016: co-circulation of the two lineages with northern hemispherical seasonality

Scant data exist about the epidemiology of influenza B in India. We set out to address the epidemiology of influenza B in a temperate region of northern India from 2010 to 2016. Outpatient and inpatient surveillance was conducted in patients presenting with acute respiratory infection in a northern Indian hospital from September 2010 till April 2016. After recording clinical data, combined nasal/throat swabs were collected and tested for influenza viruses by real time RT-PCR. Influenza A viruses were further subtyped into A/H3N2 and A/H1N1 whereas influenza B were differentiated into B/Yamagata and B/Victoria. Virus isolation, haemaggglutination inhibition testing, sequencing and phylogenetic analysis was carried out on representative samples. Of the 6879 recruited cases, influenza B was detected in 299 (4.3%). The patients presented with respiratory symptoms of varying duration; cough, fever and nasal discharge being the most common. The peaking of the activity of the circulation showed a correlation with the onset of the winter with reduced temperatures and high dry humidity. B/Victoria lineage was detected in 35.4% (n = 106/299) whereas 53.8% (n = 161/299) were B/Yamagata. The circulation in each season was dominated by one lineage which correlated with the vaccine strain, but up to 37% consisted of a different lineage. We conclude that Influenza B exhibits a northern hemispherical seasonality in temperate northern India with co-circulation of the 2 lineages of influenza B. These findings have relevance for vaccine effectiveness and argue for vaccination with a quadrivalent influenza vaccine.

Spatiotemporal Patterns and Diffusion of the 1918 Influenza Pandemic in British India

The factors that drive spatial heterogeneity and diffusion of pandemic influenza remain debated. We characterized the spatiotemporal mortality patterns of the 1918 influenza pandemic in British India and studied the role of demographic factors, environmental variables, and mobility processes on the observed patterns of spread. Fever-related and all-cause excess mortality data across 206 districts in India from January 1916 to December 1920 were analyzed while controlling for variation in seasonality particular to India. Aspects of the 1918 autumn wave in India matched signature features of influenza pandemics, with high disease burden among young adults, (moderate) spatial heterogeneity in burden, and highly synchronized outbreaks across the country deviating from annual seasonality. Importantly, we found population density and rainfall explained the spatial variation in excess mortality, and long-distance travel via railroad was predictive of the observed spatial diffusion of disease. A spatiotemporal analysis of mortality patterns during the 1918 influenza pandemic in India was integrated in this study with data on underlying factors and processes to reveal transmission mechanisms in a large, intensely connected setting with significant climatic variability. The characterization of such heterogeneity during historical pandemics is crucial to prepare for future pandemics.

Two-strain epidemic model involving fractional derivative with Mittag-Leffler kernel

In the present study, the fractional version with respect to the Atangana-Baleanu fractional derivative operator in the caputo sense (ABC) of the two-strain epidemic mathematical model involving two vaccinations has extensively been analyzed. Furthermore, using the fixed-point theory, it has been shown that the solution of the proposed fractional version of the mathematical model does not only exist but is also the unique solution under some conditions. The original mathematical model consists of six first order nonlinear ordinary differential equations, thereby requiring a numerical treatment for getting physical interpretations. Likewise, its fractional version is not possible to be solved by any existing analytical method. Therefore, in order to get the observations regarding the output of the model, it has been solved using a newly developed convergent numerical method based on the Atangana-Baleanu fractional derivative operator in the caputo sense. To believe upon the results obtained, the fractional order α has been allowed to vary between ( 0 , 1 ] , whereupon the physical observations match with those obtained in the classical case, but the fractional model has persisted all the memory effects making the model much more suitable when presented in the structure of fractional order derivatives for ABC. Finally, the fractional forward Euler method in the classical caputo sense has been used to illustrate the better performance of the numerical method obtained via the Atangana-Baleanu fractional derivative operator in the caputo sense.

Timing of respiratory syncytial virus and influenza epidemic activity in five regions of Argentina, 2007-2016

Background

Within‐country differences in the timing of RSV and influenza epidemics have not been assessed in Argentina, the eighth largest country in the world by area.

Objective

We aimed to compare seasonality for RSV and influenza both nationally and in each of the five regions to inform Argentina’s prevention and treatment guidelines.

Method

The Argentine National Laboratories and Health Institutes Administration collected respiratory specimens from clinical practices, outbreak investigations, and respiratory virus surveillance in 2007‐2016; these were tested using immunofluorescence or RT‐PCR techniques. We calculated weekly percent positive (PP) and defined season onset as >2 consecutive weeks when PP exceeded the annual mean for the respective year and region. Median season measures (onset, offset and peak) and the established mean method were calculated for each virus.

Results

An annual median 59 396 specimens were tested for RSV and 60 931 for influenza; 21–29% tested positive for RSV and 2–7% for influenza. National RSV activity began in April; region‐specific start weeks varied by 7 weeks. Duration of RSV activity did not vary widely by region (16–18 weeks in duration). National influenza activity started in June; region‐specific start weeks varied by 3 weeks. Duration of influenza epidemic activity varied more by region than that of RSV (7–13 weeks in duration).

Conclusion

In Argentina, RSV and influenza activity overlapped during the winter months. RSV season tended to begin prior to the influenza season, and showed more variation in start week by region. Influenza seasons tended to vary more in duration than RSV seasons.

Nonannual seasonality of influenza-like illness in a tropical urban setting

BACKGROUND

In temperate and subtropical climates, respiratory diseases exhibit seasonal peaks in winter. In the tropics, with no winter, peak timings are irregular.

METHODS

To obtain a detailed picture of influenza-like illness (ILI) patterns in the tropics, we established an mHealth study in community clinics in Ho Chi Minh City (HCMC). During 2009-2015, clinics reported daily case numbers via SMS, with a subset performing molecular diagnostics for influenza virus. This real-time epidemiology network absorbs 6000 ILI reports annually, one or two orders of magnitude more than typical surveillance systems. A real-time online ILI indicator was developed to inform clinicians of the daily ILI activity in HCMC.

RESULTS

From August 2009 to December 2015, 63 clinics were enrolled and 36 920 SMS reports were received, covering approximately 1.7M outpatient visits. Approximately 10.6% of outpatients met the ILI case definition. ILI activity in HCMC exhibited strong nonannual dynamics with a dominant periodicity of 206 days. This was confirmed by time series decomposition, stepwise regression, and a forecasting exercise showing that median forecasting errors are 30%-40% lower when using a 206-day cycle. In ILI patients from whom nasopharyngeal swabs were taken, 31.2% were positive for influenza. There was no correlation between the ILI time series and the time series of influenza, influenza A, or influenza B (all P > 0.15).

CONCLUSION

This suggests, for the first time, that a nonannual cycle may be an essential driver of respiratory disease dynamics in the tropics. An immunological interference hypothesis is discussed as a potential underlying mechanism.

The Pregnancy and Influenza Multinational Epidemiologic (PRIME) study: a prospective cohort study of the impact of influenza during pregnancy among women in middle-income countries

BACKGROUND

The World Health Organization identifies pregnant women as at high-risk for severe influenza, but influenza vaccines are underutilized among pregnant women. Data on influenza burden during pregnancy are largely limited to high-income countries and data on the impact of influenza on birth and perinatal outcomes are scarce.

METHODS/DESIGN

This prospective, longitudinal cohort study of pregnant women in middle-income countries is designed to address three primary objectives: 1) to evaluate the effect of laboratory-confirmed influenza during pregnancy on pregnancy and perinatal outcomes; 2) to estimate the incidences of all-cause acute respiratory illness and laboratory-confirmed influenza during pregnancy; and 3) to examine the clinical spectrum of illness associated with influenza viruses. Through a multi-country network approach, three sites aim to enroll cohorts of 1500-3000 pregnant women just before local influenza seasons. Women aged ≥ 18 years with expected delivery dates ≥ 8 weeks after the start of the influenza season are eligible. Women are followed throughout pregnancy through twice weekly surveillance for influenza symptoms (≥ 1 of myalgia, cough, runny nose, sore throat, or difficulty breathing) and have mid-turbinate nasal swabs collected for influenza virus testing during illness episodes. Primary outcomes include relative risk of preterm birth and mean birth weight among term singleton infants of women with and without reverse transcription polymerase chain reaction-confirmed influenza during pregnancy. Gestational age is determined by ultrasound at < 28 weeks gestation and birth weight is measured by digital scales using standardized methods. Sites are primarily urban in Bangkok, Thailand; Lima, Peru; and Nagpur, India. All sites recruit from antenatal clinics at referral hospitals and conduct surveillance using telephone calls, messaging applications, or home visits. Nasal swabs are self-collected by participants in Thailand and by study staff in Peru and India. During the first year (2017), sites enrolled participants during March-May in Peru and May-July in India and Thailand; 4779 women were enrolled.

DISCUSSION

This study aims to generate evidence of the impact of influenza during pregnancy to inform decisions by Ministries of Health, healthcare providers, and pregnant women in middle-income countries about the value of influenza vaccination during pregnancy.

The 2015 Outbreak of Severe Influenza in Kashmir, North India: Emergence of a New Clade of A/H1n1 Influenza Virus

Introduction: Following the initial outbreak of A/H1N1pdm09, periodic resurgences of the virus, with variable morbidity and mortality, have been reported from various parts of India including the temperate Kashmir region of northern India. An outbreak of A/H1N1 was reported in early 2015 across India with a high morbidity and mortality. We studied patients during the outbreak in Kashmir.

Methods: Patients (n=1780, age 1 month to 90 years, median 35 years) presenting with acute respiratory illness to a tertiary care hospital in Srinagar, Kashmir from October 2014 to April 2015 were recruited. After clinical data recording, combined throat and nasal swabs were collected in viral transport medium and tested by real-time RT-PCR for influenza viruses. All influenza A positive samples were further subtyped using primers and probes for A/H1N1pdm09 and A/H3 whereas influenza B samples were further subtyped into B/Yamagata and B/Victoria lineages. Virus isolation, hemagglutination inhibition testing, sequencing and phylogenetic analysis was carried out using standard procedures. Testing for H275Y mutation was done to determine sensitivity to oseltamivir. All patients received symptomatic therapy and influenza positive patients were administered oseltamivir.

Results: Of the 1780 patients, 540 (30%) required hospitalization and 533 tested positive for influenza [influenza A=517(A/H1N1pdm09=437, A/H3N2=78 with co-infection of both in 2 cases); influenza B=16 (B/Yamgata=15)]. About 14% (n=254) had been vaccinated against influenza, having received the NH 2014-15 vaccine, 27 (11.3%) of these testing positive for influenza.  Sixteen patients, including 4 pregnant females, died due to multi-organ failure. HA sequencing depicted that 2015 isolates belonged to Clade 6B.1. No H275Y mutation was reported from A/H1N1 positives.

Conclusion: Resurgent outbreak of A/H1N1pdm09, with emergence of clade 6B.1, in 2014-15 resulted in high rate of hospitalizations, morbidity and mortality. Periodic resurgences and appearance of mutants emphasize continued surveillance so as to identify newer mutations with potential for outbreaks and severe outcomes.

Comparative Study of Molecular Approaches for the Detection of Influenza Virus from Patient Samples Using Real-time PCR: Prospective Disease Burden Study in Kerala (India) from 2010 to 2016

PURPOSE OF REVIEW

Acute respiratory infections caused by influenza virus are a major cause of viral respiratory diseases globally. Surveillance of circulating subtypes and estimation of disease burden is of utmost clinical importance. Molecular surveillance and proper disease burden estimates are scarce in India although clinical influenza infections are on the rise. Our study aims to delineate the prevalent influenza subtypes in a South Indian population from cases requiring hospital visits. Using real-time polymerase chain reaction (RT-PCR), 2154 throat/nasopharyngeal swabs from patients attending Government Medical College, Thiruvananthapuram, Kerala, India, with suspected influenza-like illness, were tested for the presence of different influenza subtypes.

RESEARCH FINDINGS

Forty-three percent of specimens were positive for the influenza virus. Among these, prevalence of influenza A(H3N2), influenza B, and H1N1pdm09 was 26.7, 6.3, and 10%, respectively. Nominal co-infections were detected. An easy to use commercial kit was used for the majority of the study after proper evaluation for sensitivity and specificity against a gold standard protocol. Specific diagnosis using molecular tools caters to the urgency, and a precise measure of the disease burden and management actions are needed, especially in developing countries like India. Infection rate estimation using a sensitive RT-PCR assay signified that influenza was highly prevalent in the region. The study data generated will help understand the epidemiology of influenza in India as well as generate information for global influenza surveillance and disease burden.

Epidemiology of seasonal influenza in the Middle East and North Africa regions, 2010-2016: Circulating influenza A and B viruses and spatial timing of epidemics

BACKGROUND

There is a limited knowledge regarding the epidemiology of influenza in Middle East and North Africa.

OBJECTIVES

We described the patterns of influenza circulation and the timing of seasonal epidemics in countries of Middle East and North Africa.

METHODS

We used virological surveillance data for 2010-2016 from the WHO FluNet database. In each country, we calculated the median proportion of cases that were caused by each virus type and subtype; determined the timing and amplitude of the primary and secondary peaks; and used linear regression models to test for spatial trends in the timing of epidemics.

RESULTS

We included 70 532 influenza cases from seventeen countries. Influenza A and B accounted for a median 76.5% and 23.5% of cases in a season and were the dominant type in 86.8% and 13.2% of seasons. The proportion of influenza A cases that were subtyped was 85.9%, while only 4.4% of influenza B cases were characterized. For most countries, influenza seasonality was similar to the Northern Hemisphere, with a single large peak between January and March; exceptions were the countries in the Arabian Peninsula and Jordan, all of which showed clear secondary peaks, and some countries had an earlier primary peak (in November-December in Bahrain and Qatar). The direction of the timing of influenza activity was east to west and south to north in 2012-2013 and 2015-2016, and west to east in 2014-2015.

CONCLUSIONS

The epidemiology of influenza is generally uniform in countries of Middle East and North Africa, with influenza B playing an important role in the seasonal disease burden.

Estimation of community-level influenza-associated illness in a low resource rural setting in India

Objective

To estimate rates of community-level influenza-like-illness (ILI) and influenza-associated ILI in rural north India.

Methods

During 2011, we conducted household-based healthcare utilization surveys (HUS) for any acute medical illness (AMI) in preceding 14days among residents of 28villages of Ballabgarh, in north India. Concurrently, we conducted clinic-based surveillance (CBS) in the area for AMI episodes with illness onset ≤3days and collected nasal and throat swabs for influenza virus testing using real-time polymerase chain reaction. Retrospectively, we applied ILI case definition (measured/reported fever and cough) to HUS and CBS data. We attributed 14days of risk-time per person surveyed in HUS and estimated community ILI rate by dividing the number of ILI cases in HUS by total risk-time. We used CBS data on influenza positivity and applied it to HUS-based community ILI rates by age, month, and clinic type, to estimate the community influenza-associated ILI rates.

Findings

The HUS of 69,369 residents during the year generated risk-time of 3945 person-years (p-y) and identified 150 (5%, 95%CI: 4–6) ILI episodes (38 ILI episodes/1,000 p-y; 95% CI 32–44). Among 1,372 ILI cases enrolled from clinics, 126 (9%; 95% CI 8–11) had laboratory-confirmed influenza (A (H3N2) = 72; B = 54). After adjusting for age, month, and clinic type, overall influenza-associated ILI rate was 4.8/1,000 p-y; rates were highest among children <5 years (13; 95% CI: 4–29) and persons≥60 years (11; 95%CI: 2–30).

Conclusion

We present a novel way to use HUS and CBS data to generate estimates of community burden of influenza. Although the confidence intervals overlapped considerably, higher point estimates for burden among young children and older adults shows the utility for exploring the value of influenza vaccination among target groups.

Global influenza seasonality to inform country-level vaccine programs: An analysis of WHO FluNet influenza surveillance data between 2011 and 2016

By analyzing publicly available surveillance data from 2011-2016, we produced country-specific estimates of seasonal influenza activity for 118 countries in the six World Health Organization regions. Overall, the average country influenza activity period was 4.7 months. Our analysis characterized 100 countries (85%) with one influenza peak season, 13 (11%) with two influenza peak seasons, and five (4%) with year-round influenza activity. Surveillance data were limited for many countries. These data provide national estimates of influenza activity, which may guide planning for influenza vaccination implementation, program timing and duration, and policy development.

Epidemiological & clinical profile of influenza A (H1N1) 2009 virus infections during 2015 epidemic in Rajasthan

Background & objectives:

Pandemic influenza A (H1N1) 2009 virus emerged in 2009 and caused pandemic with high morbidity and mortality in India and worldwide. The number of H1N1-positive cases varied in different years in Rajasthan. The objective of the study was to present the epidemiological profile of pandemic influenza A (H1N1) 2009 virus cases in Rajasthan from January to March 2015.

Methods:

A retrospective descriptive, record-based analysis of suspected and confirmed cases of pandemic influenza A (H1N1) 2009 virus infection in Rajasthan, India, from January to March 2015 was performed. Testing was done as per the Centers for Disease Control guidelines at nine laboratories approved by the Government of Rajasthan. Data were analyzed in terms of demographic characteristics, clinical presentation and outcome.

Results:

Among 18,187 tested cases, 6203 (34.10%) were positive. Death occurred in 378 cases, with six per cent case fatality rate. Maximum number of cases (n=2801) and deaths (n=101) were from Jaipur zone. The highest number of cases, 47.60 per cent (2953/6203) and deaths, 52.11 per cent (197/378) were in the age group of 26-50 yr; 52.64 per cent (199/378) of deaths occurred in females. The highest number (63.5%) of deaths was from urban areas. Associated risk factors were observed in 59.44 per cent of the death cases, pregnancy being the predominant predisposing factor. In 61.92 per cent of patients, death occurred within three days of hospitalization.

Interpretation & conclusions:

H1N1 epidemic caused high morbidity and mortality in early 2015, particularly in the younger and middle-aged population and pregnant women in Rajasthan State of India. The study highlights the regular surveillance of influenza like illness, early diagnosis and timely initiation of therapy in suspected cases.

Improved Global Capacity for Influenza Surveillance

CDC’s international capacity-building program shows evidence of progress.

During 2004–2009, the Centers for Disease Control and Prevention (CDC) partnered with 39 national governments to strengthen global influenza surveillance. Using World Health Organization data and program evaluation indicators collected by CDC in 2013, we retrospectively evaluated progress made 4–9 years after the start of influenza surveillance capacity strengthening in the countries. Our results showed substantial increases in laboratory and sentinel surveillance capacities, which are essential for knowing which influenza strains circulate globally, detecting emergence of novel influenza, identifying viruses for vaccine selection, and determining the epidemiology of respiratory illness. Twenty-eight of 35 countries responding to a 2013 questionnaire indicated that they have leveraged routine influenza surveillance platforms to detect other pathogens. This additional surveillance illustrates increased health-system strengthening. Furthermore, 34 countries reported an increased ability to use data in decision making; data-driven decisions are critical for improving local prevention and control of influenza around the world.

Improved Global Capacity for Influenza Surveillance

During 2004-2009, the Centers for Disease Control and Prevention (CDC) partnered with 39 national governments to strengthen global influenza surveillance. Using World Health Organization data and program evaluation indicators collected by CDC in 2013, we retrospectively evaluated progress made 4-9 years after the start of influenza surveillance capacity strengthening in the countries. Our results showed substantial increases in laboratory and sentinel surveillance capacities, which are essential for knowing which influenza strains circulate globally, detecting emergence of novel influenza, identifying viruses for vaccine selection, and determining the epidemiology of respiratory illness. Twenty-eight of 35 countries responding to a 2013 questionnaire indicated that they have leveraged routine influenza surveillance platforms to detect other pathogens. This additional surveillance illustrates increased health-system strengthening. Furthermore, 34 countries reported an increased ability to use data in decision making; data-driven decisions are critical for improving local prevention and control of influenza around the world.

Evaluation of data sources and approaches for estimation of influenza-associated mortality in India

BACKGROUND

No estimates of influenza-associated mortality exist for India.

OBJECTIVE

To evaluate national mortality and viral surveillance data from India for assessing their appropriateness in estimating influenza-associated mortality using varied analytic approaches.

METHODS

We reviewed influenza virus surveillance data from a national influenza surveillance network. We also reviewed national mortality data from Civil Registration System (CRS), Medical Certification of Cause of Death (MCCD) and the Sample Registration System (SRS). We compared and scored the different sources of mortality data using specific criteria, including the process of cause of death assignment, sample size, proportion of ill-defined deaths, representativeness and availability of time series data. Each of these 5 parameters was scored on a scale from 1 to 5. To evaluate how to generate an influenza-associated mortality estimate for India, we also reviewed 4 methodologic approaches to assess the appropriateness of their assumptions and requirements for these data sets.

RESULTS

The influenza virus surveillance data included year-round sample testing for influenza virus and was found to be suitable for influenza mortality estimation modelling. Based on scoring for the 5 mortality data criteria, the SRS data had the highest score with 20 of 25 possible score, whereas MCCD and CRS scored 16 and 12, respectively. The SRS which used verbal autopsy survey methods was determined to be nationally representative and thus adequate for estimating influenza-associated mortality. Evaluation of the modelling methods demonstrated that Poisson regression, risk difference and mortality multiplier methods could be applied to the Indian setting.

CONCLUSION

Despite significant challenges, it is possible to estimate influenza-associated mortality in India.

Molecular and epidemiological analysis of pandemic and post-pandemic influenza A(H1N1)pdm09 virus from central India

Influenza A(H1N1)pdm09 virus pandemic struck India in 2009 and continues to cause outbreaks in its post-pandemic phase. Diminutive information is available about influenza A(H1N1)pdm09 from central India. This observational study presents epidemiological and molecular findings for the period of 6 years. Throat swab samples referred from districts of Madhya Pradesh were subjected to diagnosis of influenza A(H1N1)pdm09 following WHO guidelines. Clinical and epidemiological data were recorded and analyzed. Hemagglutinin (HA) gene sequencing and phylogenetic analysis were performed. The H275Y mutation responsible for antiviral resistance was tested using allelic real-time RT-PCR. Out of 7365 tested samples, 2406 (32.7%) were positive for influenza A(H1N1)pdm09, of which 363 (15.08%) succumbed to infection. Significant trends were observed in positivity (χ²  = 50.8; P < 0.001) and mortality (χ²  = 24.4; P < 0.001) with increasing age. Mutations having clinical and epidemiological importance were detected. Phylogenetic analysis of HA gene sequences revealed that clade 7, 6A, and 6B viruses were in circulation. Oseltamivir resistance was detected in three fatal cases. Influenza A(H1N1)pdm09 viruses having genetic diversity were detected from central India and continues to be a concern for public health. This study highlights the need of year-round monitoring by establishment of strong molecular and clinical surveillance program.

Molecular detection and characterization of Influenza 'C' viruses from western India

Since 2003, India has had a well-established influenza surveillance network, though Influenza C virus was not the focus of study. We therefore retrospectively analyzed clinical samples from Pune, western India collected during January 2009 to August 2015, by real-time RT-PCR. Three of 2530 samples of patients with influenza-like illness (ILI) or severe acute respiratory illness (SARI) showed positivity for Influenza C virus infection, while 105 and 31 samples were positive for Influenza A and B viruses respectively. Influenza C viruses were successfully isolated using the embryonated egg system and whole genomes were sequenced and analyzed phylogenetically. HE gene-based phylogeny showed that two viruses C/India/P119564/2011 and C/India P121719/2012 clustered with the C/Sao Paulo/378/82 (SP82) lineage, whereas C/India/P135047/2013 clustered with the C/Kanagawa/1/76 (KA76) lineage. The internal gene of these viruses grouped in two lineages. The PB1, PB2, M and NS genes of the study viruses grouped with C/Yamagata/26/81 (YA81), while the P3 (PA) and NP genes grouped with C/Mississippi/80 (MS80). Bayesian clock studies conclude that the Indian strains may have emerged through multiple reassortment events.

The high frequency of non-aspartic acid residues at HA222 in influenza A(H1N1) 2009 pandemic viruses is associated with mortality during the upsurge of 2015: a molecular and epidemiological study from central India

Influenza A(H1N1) viruses of the 2009 pandemic (A(H1N1)pdm09) continue to cause outbreaks in the post-pandemic period. During January to May 2015, an upsurge of influenza was recorded that resulted in high fatality in central India. Genetic lineage, mutations in the hemagglutinin (HA) gene and infection by quasi-species are reported to affect disease severity. The objective of this study is to present the molecular and epidemiological trends during the 2015 influenza outbreak in central India. All the referred samples were subjected to qRT–PCR for diagnosis. HA gene sequencing (23 survivors and 24 non-survivors) and cloning were performed and analyzed using Molecular Evolutionary Genomic Analyzer (MEGA 5·05). Of the 3625 tested samples, 1607 (44·3%) were positive for influenza A(H1N1)pdm09, of which 228 (14·2%) individuals succumbed to death. A significant trend was observed in positivity (P = 0·003) and mortality (P < 0·0001) with increasing age. The circulating A(H1N1)pdm09 virus was characterized as belonging to clade-6B. Clinically significant mutations were detected. Patients infected with the quasi-species of the virus had a greater risk of death (P = 0·009). This study proposes a robust molecular and clinical surveillance program for the detection and characterization of the virus, along with prompt treatment protocols to prevent outbreaks.

Influenza seasonality goes south in the Yucatan Peninsula: The case for a different influenza vaccine calendar in this Mexican region

INTRODUCTION

While vaccination may be relatively straightforward for regions with a well-defined winter season, the situation is quite different for tropical regions. Influenza activity in tropical regions might be out of phase with the dynamics predicted for their hemispheric group thereby impacting the effectiveness of the immunization campaign.

OBJECTIVE

To investigate how the climatic diversity of Mexico hinders its existing influenza immunization strategy and to suggest that the hemispheric vaccine recommendations be tailored to the regional level in order to optimize vaccine effectiveness.

METHODS

We studied the seasonality of influenza throughoutMexico by modeling virological and mortality data.De-trended time series of each Mexican state were analyzed by Fourier decomposition to describe the amplitude and timing of annual influenza epidemic cycles and to compare with each the timing of the WHO's Northern and Southern Hemispheric vaccination schedule.

FINDINGS

The timings of the primary (major) peaks of both virological and mortality data for most Mexican states are well aligned with the Northern Hemisphere winter (December-February) and vaccine schedule. However, influenza peaks in September in the three states of the Yucatan Peninsula. Influenza-related mortality also peaks in September in Quintana Roo and Yucatan whereas it peaks in May in Campeche. As the current timing of vaccination in Mexico is between October and November, more than half of the annual influenza cases have already occurred in the Yucatan Peninsula states by the time the Northern Hemispheric vaccine is delivered and administered.

CONCLUSION

The current Northern Hemispheric influenza calendar adopted for Mexico is not optimal for the Yucatan Peninsula states thereby likely reducing the effectiveness of the immunization of the population. We recommend that Mexico tailor its immunization strategy to better reflect its climatologic and epidemiological diversity and adopt the WHO Southern Hemisphere influenza vaccine and schedule for the Yucatan Peninsula.

Year-round influenza immunisation during pregnancy in Nepal: a phase 4, randomised, placebo-controlled trial

BACKGROUND

Influenza immunisation during pregnancy is recommended but not widely implemented in some low-income regions. We assessed the safety and efficacy in mothers and infants of year-round maternal influenza immunisation in Nepal, where influenza viruses circulate throughout the year.

METHODS

In this phase 4, randomised, placebo-controlled trial, we enrolled two consecutive sequential annual cohorts of pregnant women from the Sarlahi district in southern Nepal. We randomised mothers 1:1 to receive seasonally recommended trivalent inactivated influenza vaccine or saline placebo in blocks of eight, stratified by gestational age at enrolment (17-25 weeks vs 26-34 weeks). Women were eligible if they were married, 15-40 years of age, 17-34 weeks' gestation at enrolment, and had not previously received any influenza vaccine that season. We collected serum samples before and after immunisation, and cord blood from a subset of women and infants. Staff masked to allocation made home visits every week from enrolment to 6 months after delivery. Midnasal swabs for respiratory virus PCR testing were collected during maternal acute febrile respiratory infections, and from infants with any respiratory symptom. We assessed vaccine immunogenicity, safety, and three primary outcomes: the incidence of maternal influenza-like illness in pregnancy and 0-180 days postpartum, the incidence of low birthweight (<2500 g), and the incidence of laboratory-confirmed infant influenza disease from 0 to 180 days. This trial is registered with ClinicalTrials.gov, number NCT01034254.

FINDINGS

From April 25, 2011, to Sept 9, 2013, we enrolled 3693 women in two cohorts of 2090 (1041 assigned to placebo and 1049 to vaccine) and 1603 (805 assigned to placebo and 798 to vaccine), with 3646 liveborn infants (cohort 1, 999 in placebo group and 1010 in vaccine group; cohort 2, 805 in placebo group and 798 in vaccine group). Immunisation reduced maternal febrile influenza-like illness with an overall efficacy of 19% (95% CI 1 to 34) in the combined cohorts; 9% efficacy (-16 to 29) in the first cohort, and 36% efficacy (9 to 55) in the second cohort. For laboratory-confirmed influenza infections in infants aged 0-6 months, immunisation had an overall efficacy for the combined cohorts of 30% (95% CI 5 to 48); in the first cohort, the efficacy was 16% (-19 to 41), and in the second cohort it was 60% (26 to 88). Maternal immunisation reduced the rates of low birthweight by 15% (95% CI 3-25) in both cohorts combined. The rate of small for gestational age infants was not modified by immunisation. The number of adverse events was similar regardless of immunisation status. Miscarriage occurred in three (0·2%) participants in the placebo group versus five (0·3%) in the vaccine group, stillbirth occurred in 31 (1·7%) versus 33 (1·8%), and congenital defects occurred in 18 (1·0%) versus 20 (1·1%). Five women died in the placebo group and three died in the vaccine group. The number of infant deaths at age 0-6 months was similar in each group (50 in the placebo group and 61 in the vaccine group). No serious adverse events were associated with receipt of immunisation.

INTERPRETATION

Year-round maternal influenza immunisation significantly reduced maternal influenza-like illness, influenza in infants, and low birthweight over the entire course of the study, indicating the strategy could be useful in subtropical regions.

FUNDING

Bill & Melinda Gates Foundation.

Influenza A(H1N1)pdm09 outbreak detected in inter-seasonal months during the surveillance of influenza-like illness in Pune, India, 2012-2015

An outbreak of influenza A(H1N1)pdm09 was detected during the ongoing community-based surveillance of influenza-like illness (ILI). Among reported 119 influenza A(H1N1)pdm09 cases (59 cases in the year 2012 and 60 cases in 2015) in summer months, common clinical features were fever (100%), cough (90·7%), sore throat (85·7%), nasal discharge (48·7%), headache (55·5%), fatigue (18·5%), breathlessness (3·4%), and ear discharge (1·7%). Rise in ILI cases were negatively correlated with the seasonal factors such as relative humidity (Karl Pearson's correlation coefficient, i.e. r = -0·71 in the year 2012 and r = -0·44 in the year 2015), while rise in ILI cases were positively correlated with the temperature difference (r = 0·44 in the year 2012 and r = 0·77 in the year 2015). The effective reproduction number R, was estimated to be 1·30 in 2012 and 1·64 in 2015. The study highlights the rise in unusual influenza activity in summer month with high attack rate of ILI among children aged ⩽9 years. Children in this age group may need special attention for influenza vaccination. Influenza A(H1N1)pdm09 outbreak was confirmed in inter-seasonal months during the surveillance of ILI in Pune, India, 2012-2015.

Characteristics of seasonal influenza A and B in Latin America: Influenza surveillance data from ten countries

INTRODUCTION

The increased availability of influenza surveillance data in recent years justifies an actual and more complete overview of influenza epidemiology in Latin America. We compared the influenza surveillance systems and assessed the epidemiology of influenza A and B, including the spatio-temporal patterns of influenza epidemics, in ten countries and sub-national regions in Latin America.

METHODS

We aggregated the data by year and country and characteristics of eighty-two years were analysed. We calculated the median proportion of laboratory-confirmed influenza cases caused by each virus strain, and compared the timing and amplitude of the primary and secondary peaks between countries.

RESULTS

37,087 influenza cases were reported during 2004-2012. Influenza A and B accounted for a median of 79% and, respectively, 21% of cases in a year. The percentage of influenza A cases that were subtyped was 82.5%; for influenza B, 15.6% of cases were characterized. Influenza A and B were dominant in seventy-five (91%) and seven (9%) years, respectively. In half (51%) of the influenza A years, influenza A(H3N2) was dominant, followed by influenza A(H1N1)pdm2009 (41%) and pre-pandemic A(H1N1) (8%). The primary peak of influenza activity was in June-September in temperate climate countries, with little or no secondary peak. Tropical climate countries had smaller primary peaks taking place in different months and frequently detectable secondary peaks.

CONCLUSIONS

We found that good influenza surveillance data exists in Latin America, although improvements can still be made (e.g. a better characterization of influenza B specimens); that influenza B plays a considerable role in the seasonal influenza burden; and that there is substantial heterogeneity of spatio-temporal patterns of influenza epidemics. To improve the effectiveness of influenza control measures in Latin America, tropical climate countries may need to develop innovative prevention strategies specifically tailored to the spatio-temporal patterns of influenza in this region.

Influenza in the Asia-Pacific region: Findings and recommendations from the Global Influenza Initiative

The fourth roundtable meeting of the Global Influenza Initiative (GII) was held in Hong Kong, China, in July 2015. An objective of this meeting was to gain a broader understanding of the epidemiology, surveillance, vaccination policies and programs, and obstacles to vaccination of influenza in the Asia-Pacific region through presentations of data from Australia, Hong Kong, India, Indonesia, Malaysia, New Zealand, the Philippines, Taiwan, Thailand, and Vietnam. As well as a need for improved levels of surveillance in some areas, a range of factors were identified that act as barriers to vaccination in some countries, including differences in climate and geography, logistical challenges, funding, lack of vaccine awareness and education, safety concerns, perceived lack of vaccine effectiveness, and lack of inclusion in national guidelines. From the presentations at the meeting, the GII discussed a number of recommendations for easing the burden of influenza and overcoming the current challenges in the Asia-Pacific region. These recommendations encompass the need to improve surveillance and availability of epidemiological data; the development and publication of national guidelines, where not currently available and/or that are in line with those proposed by the World Health Organization; the requirement for optimal timing of vaccination programs according to local or country-specific epidemiology; and calls for advocacy and government support of vaccination programs in order to improve availability and uptake and coverage. In conclusion, in addition to the varied epidemiology of seasonal influenza across this diverse region, there are a number of logistical and resourcing issues that present a challenge to the development of optimally effective vaccination strategies and that need to be overcome to improve access to and uptake of seasonal influenza vaccines. The GII has developed a number of recommendations to address these challenges and improve the control of influenza.

Respiratory viruses in acute exacerbations of chronic obstructive pulmonary disease

Objective:

Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) cause significant morbidity, mortality, and an inexorable decline of lung function. Data from developed countries have shown viruses to be important causes of AECOPD, but data from developing countries like India are scant. We set out to determine the contribution of viruses in the causation of hospitalized patients with AECOPD.

Methods:

Twin nasopharyngeal/oropharyngeal swabs collected from 233 patients admitted with an acute AECOPD and tested for respiratory viruses including respiratory syncytial virus A and B, parainfluenza were (PIV) 1, 2, 3, and 4, human metapneumovirus (hMPV) A and B, influenza A and B, enterovirus, corona NL65, OC43, and 229E viruses, adenovirus 2 and 4, rhinovirus, and bocavirus, by duplex real time reverse-transcription polymerase chain reaction (qRT-PCR) using CDC approved primers and probes. Samples positive for influenza A were subtyped for A/H1N1pdm09 and A/H3N2 whereas influenza B samples were subtyped into B/Yamagata and B/Victoria subtypes, using primers and probes recommended by CDC, USA.

Results:

Respiratory viruses were detected in 46 (19.7%) cases, influenza A/H3N2 and rhinoviruses being the most common viruses detected. More than one virus was isolated in four cases consisting of hMPV-B + adeno-2 + Inf-B; rhino + H3N2, PIV-1 + rhino; and PIV-1+ hMPV-B in one case each. Ancillary supportive therapeutic measures included bronchodilators, antibiotics, steroids, and ventilation (noninvasive in 42 and invasive in 4). Antiviral therapy was instituted in influenza-positive patients. Three patients with A/H3N2 infection died during hospitalization.

Conclusions:

We conclude that respiratory viruses are important contributors to AECOPD in India. Our data calls for prompt investigation during an exacerbation for viruses to obviate inappropriate antibiotic use and institute antiviral therapy in viral disease amenable to antiviral therapy. Appropriate preventive strategies like influenza vaccination also need to be employed routinely.

National Influenza Surveillance in the Philippines from 2006 to 2012: seasonality and circulating strains

Background

The results of routine influenza surveillance in 13 regions in the Philippines from 2006 to 2012 are presented, describing the annual seasonal epidemics of confirmed influenza virus infection, seasonal and alert thresholds, epidemic curve, and circulating influenza strains.

Methods

Retrospective analysis of Philippine influenza surveillance data from 2006 to 2012 was conducted to determine seasonality with the use of weekly influenza positivity rates and calculating epidemic curves and seasonal and alert thresholds using the World Health Organization (WHO) global epidemiological surveillance standards for influenza.

Results

Increased weekly influenza positive rates were observed from June to November, coinciding with the rainy season and school opening. Two or more peaks of influenza activity were observed with different dominant influenza types associated with each peak. A-H1N1, A-H3N2, and two types of B viruses circulated during the influenza season in varying proportions every year. Increased influenza activity for 2012 occurred 8 weeks late in week 29, rather than the expected week of rise of cases in week 21 as depicted in the established average epidemic curve and seasonal threshold. The intensity was severe going above the alert threshold but of short duration. Southern Hemisphere vaccine strains matched circulating influenza virus for more surveillance years than Northern Hemisphere vaccine strains.

Conclusions

Influenza seasonality in the Philippines is from June to November. The ideal time to administer Southern Hemisphere influenza vaccine should be from April to May. With two lineages of influenza B circulating annually, quadrivalent vaccine might have more impact on influenza control than trivalent vaccine. Establishment of thresholds and average epidemic curve provide a tool for policy-makers to assess the intensity or severity of the current influenza epidemic even early in its course, to help plan more precisely resources necessary to control the outbreak. Influenza surveillance activities should be continued in the Philippines and funding for such activities should already be incorporated into the Philippine health budget.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-2087-9) contains supplementary material, which is available to authorized users.

Influenza Seasonality in the Tropics and Subtropics - When to Vaccinate?

BACKGROUND

The timing of the biannual WHO influenza vaccine composition selection and production cycle has been historically directed to the influenza seasonality patterns in the temperate regions of the northern and southern hemispheres. Influenza activity, however, is poorly understood in the tropics with multiple peaks and identifiable year-round activity. The evidence-base needed to take informed decisions on vaccination timing and vaccine formulation is often lacking for the tropics and subtropics. This paper aims to assess influenza seasonality in the tropics and subtropics. It explores geographical grouping of countries into vaccination zones based on optimal timing of influenza vaccination.

METHODS

Influenza seasonality was assessed by different analytic approaches (weekly proportion of positive cases, time series analysis, etc.) using FluNet and national surveillance data. In case of discordance in the seasonality assessment, consensus was built through discussions with in-country experts. Countries with similar onset periods of their primary influenza season were grouped into geographical zones.

RESULTS

The number and period of peak activity was ascertained for 70 of the 138 countries in the tropics and subtropics. Thirty-seven countries had one and seventeen countries had two distinct peaks. Countries near the equator had secondary peaks or even identifiable year-round activity. The main influenza season in most of South America and Asia started between April and June. The start of the main season varied widely in Africa (October and December in northern Africa, April and June in Southern Africa and a mixed pattern in tropical Africa). Eight "influenza vaccination zones" (two each in America and Asia, and four in Africa and Middle East) were defined with recommendations for vaccination timing and vaccine formulation. The main limitation of our study is that FluNet and national surveillance data may lack the granularity to detect sub-national variability in seasonality patterns.

CONCLUSION

Distinct influenza seasonality patterns, though complex, could be ascertained for most countries in the tropics and subtropics using national surveillance data. It may be possible to group countries into zones based on similar recommendations for vaccine timing and formulation.

Clinical Presentation and Birth Outcomes Associated with Respiratory Syncytial Virus Infection in Pregnancy

Background

Respiratory syncytial virus (RSV) is the most important cause of viral pneumonia in children worldwide. A maternal vaccine may protect both the mother and infant from RSV illness. The epidemiology and clinical presentation of RSV in pregnant and postpartum women is not well-described.

Methods

Data were collected from a prospective, randomized trial of influenza immunization in pregnant women in rural southern Nepal. Women were enrolled in their second trimester of pregnancy and followed until six months postpartum. Active weekly home-based surveillance for febrile respiratory illness was performed. Mid-nasal swabs collected with episodes of respiratory illness were tested for RSV by real-time polymerase chain reaction.

Results

RSV was detected in 14 (0.4%) illness episodes in 3693 women over 3554 person-years of surveillance from 2011–2014. RSV incidence was 3.9/1000 person-years overall, and 11.8/1000 person-years between September and December. Seven (50%) women sought care for RSV illness; none died. Of the 7 (50%) illness episodes during pregnancy, all had live births with 2 (29%) preterm births and a median birthweight of 3060 grams. This compares to 469 (13%) preterm births and a median birthweight of 2790 grams in women without RSV during pregnancy. Of the 7 mothers with postpartum RSV infection, RSV was detected in 4 (57%) of their infants.

Conclusions

RSV was an uncommon cause of febrile respiratory illness in mothers during pregnancy in Nepal. These data will inform prevention and therapeutic strategies against RSV in resource-limited settings.

Divergent seasonal patterns of influenza types A and B across latitude gradient in Tropical Asia

Introduction

Influenza circulation in tropics and subtropics reveals a complex seasonal pattern with year‐round circulation in some areas and biannual peaks in others.

Methods

We analyzed influenza surveillance data from nine countries around southern and southeastern Asia spanning latitudinal gradient from equatorial to temperate zones to further characterize influenza type‐specific seasonality in the region. We calculated proportion of positives by month out of positives during that year and adjust for variation in samples tested and positivity in these countries.

Results

Influenza A epidemics were identified between November and March during winters in areas lying above 30°N latitude, during monsoon months of June–November in areas between 10° and 30°N latitude, and no specific seasonality for influenza A virus circulation in areas lying closer to the equator. Influenza B circulation coincided with influenza A circulation in areas lying above 30°N latitude; however, in areas south of 30°N Asia, influenza B circulated year round at 3–8% of annual influenza B positives during most months with less pronounced peaks during post‐monsoon period.

Conclusion

Even though influenza B circulates round the year in most areas of the tropical regions of southern and southeastern Asia, the most appropriate time for influenza vaccination using the most recent WHO recommended vaccine would be prior to the monsoon season conferring protection against influenza A and B peaks.

Influenza Illness in Pregnant Indian Women: A Cross-Sectional Study

Data about burden of influenza in pregnancy in India are scant. In order to assess the contribution of influenza to acute respiratory illness (ARI) in pregnancy, 266 north Indian pregnant females with febrile ARI were studied from December 2014 to May 2015. Twin nasopharyngeal/oropharyngeal swabs were obtained and tested for influenza viruses by RT-PCR. Fifty (18.8%) patients tested positive for influenza (A/H1N1pdm09 in 41, A/H3N2 in 8, and influenza B Yamagata in 1). Rigors, headache, and a family history of ARI were significantly more frequent in influenza positive patients. Oseltamivir and supportive therapy were administered to all confirmed cases. Nine influenza positive cases needed hospitalization for their respiratory illness, and 5 developed respiratory failure. Of these, 4 (3 in third trimester) succumbed to their illness. We conclude that influenza viruses are a cause of significant morbidity and mortality among pregnant females with ARI in north India. As such, appropriate preventive strategies of influenza vaccination and early initiation of antiviral therapy during illness are stressed.

The Saudi Thoracic Society guidelines for influenza vaccinations

Influenza viruses are responsible for the influenza outbreaks that lead to significant burden and cause significant morbidity and mortality worldwide. Based on the core proteins, influenza viruses are classified into three types, A, B, and C, of which only A and B cause significant human disease and so the vaccine is directed against these two subtypes only. The effectiveness of the vaccine depends on boosting the immune system against the serotypes included within it. As influenza viruses undergo periodic changes in their antigen, the vaccine is modified annually to ensure susceptibility. In contrast to other countries, Saudi Arabia faces a unique and challenging situation due to Hajj and Umrah seasons, when millions of people gather at the holy places in Mecca and Madinah, during which influenza outbreaks are commonly found. Such challenges making the adoption of strict vaccination strategy in Saudi Arabia is of great importance. All efforts were made to develop this guideline in an easy-to-read form, making it very handy and easy to use by health care workers. The guideline was designed to provide recommendations for problems frequently encountered in real life, with special consideration for special situations such as Hajj and Umrah seasons and pregnancy.